Twist drill and like metal-cutting tools



June 11,' 1940. J. sAY

TWIST DRILL AND LIKE METAL-CUTTING TOOLS Filed July 22, 1957 l l l l h H U n. H I;

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uhhh hhfil l l hhu I l I I I i l l UNITED STATES PATENT OFFICE TWIST DRILL AND LIKE METAL-CUTTING TOOLS James Say, Hammersmith, London, England Application July 22, 1937, Serial No. 155,116 In Great Britain August 1, 1936 2 Claims. (Cl. 77-67) This invention relates to improvements in to those generally used in the process of gun twist drills and like metal-cutting tools and has boring, wherein a denotes a tool or cutter in-, for its object to provide means whereby the metal serted in a holder or shank, b the cutting lip of chips removed by the drill or like tool are brothe tool a and 1c the projections or ribs formed- 5 ken up during the process of cutting. on the cutting lip of the tool. 5

The improvement is more particularly appli- The backing off of clearance areas d behind cable to spiral or straight fluted drills but can the cutting lips b and shank clearances are with advantage be applied to most types of borformed in the usual way, and the projections 0 ing tools where an advanced chip-breaker is being raised above the cutting lips b are always preferred. in advance of the cutting lips should the drill or 10 In applying the improvement tospiral or tool be reground, so that a permanent advanced straight fluted drills, as an example, I provide on chip-breaker is provided. the cutting edge of the flute one or more pro- I claim: jections according to the size of the drill, the n a drill including a land having at its 5 projections running the full length of the flute. ow r end a cutting e, a ur ace t p a e o The projections or ribs may be milled at the same which is substantially radial to the curvature of time as the flute of the drill is being produced, said land, an elongate p i n n he fac andmay be of any preferred form, but convex of said surface extending longitudinally thereor flat projections e prefe r d, of, the Walls of said projection being perpendicu- According to this invention the cutting sides t0 the face of the Su h top of s d "0 of the flutes may have a plurality of projections projection being pa el W t said face, the or ribs of uniform size and shape on each flute, transverse Width of Said DrOjeCtiOh being fl the ribs on each flute being symmetrical and of than the height 0 Said P j i e end equal distance from the centre of the drill,but cf a d elongate projection te m natin in a ribs or projections in different flutes may be Cutting e located in a e a d abov 25 formed at different distances from the centre the Cutting e on the e to p d a P of the drill or be formed of different formation manent advanced chip-breaker, and h Ot er or shape end of said projection terminating at the upper In the accompanying drawingf Said Surface- 3 Figure 1 is a side view of a twist drill in 2. In a drill, including a land and a groove, accordance with this invention, said land terminating at its lower end in a Clit- Figure 2 is an end view of the drill. ting edge, an elongate projection on the face of Figure 3 is a side view of a straight fluted drill the groove extendihgtlengitudinelly and inwardin accordance with this invention. 3' t e the walls of said projection being D Figure 4 is an end view of this drill. pendicular to the face of the e, e top 35 Figure 5 is a, ide view of a, boring t i of said projection being parallel with said face, accordance with this invention, the transverse Width of said projection being Figure 6 is an end view of this boring tool. greater t n the height of a projection, n

' Referring to Figures 1, 2, 3 and 4, similar letend of said elon a e projection terminating in a 40 ters denote similar parts. As illustrated in the cuttin ed e ca e in advance of, and above, to drawing, (1 denotes the flutes of the drills, b the the Cutting d e on the la d to provide a a D cutting lips of the flutes a, and c the projections manent advanced chip-brea and e her or ribs formed on the cutting sidesof the flutes d of Said Projection terminating at the uppe and having the same pitch asthe flutes. end of said surface. I 4.5 Figures 5 and 6 illustrate a boring tool similar JAMES SAY. 

